<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>Title</title>
</head>
<body>
<div id="app">
  <h2>{{firstName + ' ' +lastName}}</h2>
  <h2>{{fullName}}</h2>
</div>
<script src="../js/vue.js"></script>
<script>
  const vm=new Vue({
    el:'#app',
    data:{
      message:'',
      firstName:'严浩然',
      lastName:'金瑞昌'
    },
    computed:{//计算属性()  里面存在缓存
      fullName:function () {
        return this.firstName + ' ' +this.lastName
      }
    }
  })
</script>

</body>
</html>